UTT-901 User Manual5innovative technology, UTT-901 IP Gateway features market leadingsuperb sound quality and rich functionalities.3.1 key Featuresz Support two models: Bridge and Router(NAT&NAPT)z Network Protocols: TCP/UDP/IP, ICMP, HTTP, DHCP Client(WANInterface), DHCP Server(LAN Interface), DNS Client, DNS Relay,SNTP, PPPoE, FTP, TFTPz VoIP Protocols: SIP (RFC2976,RFC3261, RFC3262, RFC3264,RFC3265,RFC3515,RFC3581)z Voice Codecs: G.711(A-law/U-law), G.729A/B, G.726z Redundancy SIP server (or Gate Keeper): Can auto swap addressbetween two servers addressz NAT transversal: Support STUN client. Can modify SIP register port,HTTP server port, Telnet server port and RTP portz Support two SIP server synchronously: Can register two different SIPserver, and can make a call by either proxyz Support standard voice features such as numeric Caller ID Display,